burned rss,404 mistake

few days before,i set the URL Rewrite to my website.and my feed did not output from then on.(the file .htaccess is empty, i did not code any character.)

https://sudasuta.com/?feed=rss2 or https://sudasuta.com/feed/

you can see and feed these on browsers.all is correct.
but when you burn it on google FeedBurner:
“An error occurred connecting to the URL: Error getting URL: 404 – Not Found”

i check these two feeds on https://feedvalidator.org
the tip is:
“Sorry:This feed does not validate.Server returned HTTP Error 404: Not Found [help]”

how could i fix this problem? and what may cause this problem?

thanks. T-T